fix: suppress Chromium/Brave stderr noise during theme switch (#5285)

Redirect stderr to /dev/null alongside stdout when refreshing
browser platform policy, preventing shared_memory_switch errors
from cluttering the terminal.

bin/omarchy-theme-set-browser

@@ -14,11 +14,11 @@ if omarchy-cmd-present chromium || omarchy-cmd-present brave; then
 
   if omarchy-cmd-present chromium; then
     echo "{\"BrowserThemeColor\": \"$THEME_HEX_COLOR\", \"BrowserColorScheme\": \"device\"}" | tee "/etc/chromium/policies/managed/color.json" >/dev/null
-    chromium --refresh-platform-policy --no-startup-window >/dev/null
+    chromium --refresh-platform-policy --no-startup-window &>/dev/null
   fi
 
   if omarchy-cmd-present brave; then
     echo "{\"BrowserThemeColor\": \"$THEME_HEX_COLOR\", \"BrowserColorScheme\": \"device\"}" | tee "/etc/brave/policies/managed/color.json" >/dev/null
-    brave --refresh-platform-policy --no-startup-window >/dev/null
+    brave --refresh-platform-policy --no-startup-window &>/dev/null
   fi
 fi